Enhancing Decision Making to Help Manage Freshwater Resources: Using NASA's GPM and NOAA's PERSIANN-CDR to Provide Near Real-Time Precipitation Estimates for Decision Makers in the U. S. Affiliated Pacific Islands (USAPI)

The United States Affiliated Pacific Islands (USAPI) are extremely vulnerable to the precipitation shifts associated with the El Niño Southern Oscillation (ENSO). In the past, scientists in the region utilized a spatially-limited, in situ-based, ENSO climatology to inform their seasonal precipitation outlooks. To fill this spatial gap, the NASA DEVELOP Pacific Water Resources I team successfully delivered an updated, ENSO-based precipitation climatic reference atlas derived primarily using remotely-sensed data from the National Oceanic and Atmospheric Administration (NOAA) Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Records (PERSIANN-CDR). While the atlas has been heavily utilized by scientists in the region, it is somewhat limited in that it does not provide near real-time precipitation estimates. The NASA DEVELOP Pacific Water Resources II project filled this limitation through the utilization of near real-time precipitation data from NASA’s Global Precipitation Measurement (GPM) mission which provides 30-minute rainfall estimates at 0.1° spatial resolution.  To fully understand whether satellite-derived rainfall estimates from GPM can be used operationally in a near-real-time anomaly product, an analysis comparing the satellite products (PERSIANN-CDR, GPM) to 27 Global Historical Climate Network Daily (GHCN-D) stations in the west Pacific was completed. Results suggest that daily, monthly, and seasonal trends in raw station values and satellite-derived rainfall estimates were consistent. Therefore, results herein confirm the usefulness of using GPM precipitation estimates to accurately capture the recent seasonal precipitation trends found across the USAPI. The end results from this project provided a suite of near real-time precipitation estimate tools that can be used by decision makers in the region to help mitigate and/or adapt to ongoing and future water resource emergencies.